A study of deep convection in the Labrador Sea was undertaken by several investigators from several different countries. The observational program consisted of repeated hydrographic surveys, free-drifting subsurface floats, and moored instrumentation. German and Canadian scientists moored an array along a transect extending from the Labrador coastline into the center of the basin. The array consisted of several current meter moorings located in the boundary current and in the deep convection regions as well as a tomography array and a meteorological buoy. Additionally, a profiling CTD was moored in the boundary current region by J. Toole.
Between June 1995 and August 1997, our group at URI deployed an inverted echo sounder (IES) in the central portion of the Labrador Sea, near the OWS Bravo site. For the final 4-month portion of the record, bottom pressure was also measured by the IES.
In November 1996, three additional inverted echo sounders with bottom pressure gauges (PIES) were moored in the boundary current region along the same line as the current meter moorings. In July 1997, the PIES recovered from the deep convection region was relocated to the onshore portion of boundary current array. The instruments were recovered during July 1998.
Dr. Mark Prater (URI) integrated the measurements taken at OWS Bravo between the sea surface and 1500 m to determine heat content and to simulate IES travel time measurements. A very tight linear relationship (correlation coefficent exceeding 99%) was found to exist between acoustic travel time and heat content indicating that IESs can be used quite successfully in this oceanic region as calorimeters.
A two-year-long record of heat content has been obtained from the IES deployed in the central portion of the Labrador Sea near the OWS Bravo site. The results presented here show that the variability in heating occurs over several timescales.
Return to the Dynamics of Ocean Currents and Fronts Homepage